Tìm X (lời giải đầy đủ):
a.9/14 : X = 3/7
b.7/15 x X = 7/10
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a: =18/70+4/5=18/70+56/70=74/70=37/35
b: =4/5-3/4=16/20-15/20=1/20
a) \(\dfrac{2}{7}\times\dfrac{9}{10}+\dfrac{4}{5}=\dfrac{18}{70}+\dfrac{4}{5}=\dfrac{9}{35}+\dfrac{4}{5}=\dfrac{9}{35}+\dfrac{28}{35}=\dfrac{37}{35}\)
b) \(\dfrac{12}{15}-\dfrac{1}{2}:\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{1}{2}\times\dfrac{3}{2}=\dfrac{12}{15}-\dfrac{3}{4}=\dfrac{4}{5}-\dfrac{3}{4}=\dfrac{16}{20}-\dfrac{15}{20}=\dfrac{1}{20}\)
\(a,\Leftrightarrow x=7-4=3\\ b,\Leftrightarrow2x=-18+5=-13\\ \Leftrightarrow x=-\dfrac{13}{2}\\ c,\Leftrightarrow x-21=10\\ \Leftrightarrow x=31\\ d,\Leftrightarrow-12-x+19=0\\ \Leftrightarrow7-x=0\\ \Leftrightarrow x=7\)
a, <=> x=7-4
<=> x=3
b, 2x= -18 +5
<=>2x=-13
<=> x= -13/2
c, <=> x -21=-10
<=> x= -10 +21
<=> x=11
d, <=> -12+19 -x=0
<=> 7-x=0
<=> x=7
`3/7xx14/5+32/5xx3/7+3/7xx9/5`
`=3/7xx(14/5+32/5+9/5)`
`=3/7xx55/5`
`=3/7xx5`
`=15/7`
\(=\frac{3}{7}\times[\frac{14}{5}+\frac{32}{5}+\frac{9}{5}]=\frac{3}{7}\times\frac{55}{5}=\frac{3}{7}\times11=\frac{33}{7}\)
1.
7/15:(1/2-9/10xX)-1/6=13/6
=>7/15:(1/2-9/10xX)=13/6+1/6
=>7/16:(1/2-9/10xX)=7/3
=>1/2-9/10xX=7/16:7/3
=>1/2-9/10xX=3/16
=>9/10xX=1/2-3/16
=>9/10xX=5/16
=>X=5/16:9/10
=>X=25/72
-x-12=-15+7-14
-x-12=-8-14
-x-12=-22
=> -x= -22+12
=> -x=-10
=> x=10
a) \(-65-\left(x+15\right)+105=0\)
\(-65-\left(x+15\right)=-105\)
\(x+15=-65-\left(-105\right)\)
\(x+15=40\)
\(x=25\)
b) |-6| + (-9) - (x+1) = 7
-3- (x+1) =7
x+1 = -10
x = -11
c)\(\left|5-x\right|+\left(-25+7\right)=-3-\left(-10\right)\)
\(\left|5-x\right|+\left(-18\right)=7\)
\(\left|5-x\right|=25\)
\(\Rightarrow\orbr{\begin{cases}5-x=25\\5-x=-25\end{cases}\Rightarrow\orbr{\begin{cases}x=-20\\x=30\end{cases}}}\)
d) \(28-\left|x+6\right|+\left(-2\right)=0\)
\(28-\left|x+6\right|=2\)
\(\left|x+6\right|=26\)
\(\Rightarrow\orbr{\begin{cases}x+6=26\\x+6=-26\end{cases}\Rightarrow\orbr{\begin{cases}x=20\\x=-32\end{cases}}}\)
e) \(x-\left(13-15\right)=5+\left(10-x\right)-\left(-1\right)\)
\(x+2=5+10-x+1\)
\(x+2=16-x\)
\(x+x=16-2\)
\(2x=14\)
\(x=7\)
f) \(-120-\left(x-5\right)=125\)
\(x-5=-120-125\)
\(x-5=-245\)
\(x=-240\)
g) \(10-\left(-5+2\right)+\left(-9\right)=\left(-20+7\right)-x\)
\(-16=-13-x\)
\(x=-13+16\)
\(x=3\)
`( 9 xx 6 xx 5 xx 7 )/( 19 xx 7 xx 2 xx 3 )`
`= ( 9 xx 2 xx 3 xx 7 xx 5 )/( 19 xx 7 xx 2 xx 3 )`
`= (9xx5)/19`
`= 45/19`
a.\(\dfrac{9}{14}:x=\dfrac{3}{7}\)
\(x=\dfrac{9}{14}:\dfrac{3}{7}\)
\(x=\dfrac{3}{2}\)
b.\(\dfrac{7}{15}\times x=\dfrac{7}{10}\)
\(x=\dfrac{7}{10}:\dfrac{7}{15}\)
\(x=\dfrac{3}{2}\)
a: x=9/14:3/7=9/14x7/3=63/42=3/2
b: x=7/10:7/15=15/10=3/2